Unaudited Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Cumulative effect, period of adoption, adjustment	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative effect, period of adoption, adjustment	Treasury Share Amount	Total Mr. Cooper Stockholders’ Equity	Total Mr. Cooper Stockholders’ Equity Cumulative effect, period of adoption, adjustment	Non-controlling Interests
Shares outstanding, beginning balance (in shares) at Dec. 31, 2019			1,000	91,118
Stockholders' equity, beginning balance at Dec. 31, 2019	$ 2,231	$ 7	$ 0	$ 1	$ 1,109	$ 1,122	$ 7	$ 0	$ 2,232	$ 7	$ (1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan (in shares)				852
Shares issued / (surrendered) under incentive compensation plan	(5)				(5)				(5)
Share-based compensation	4				4				4
Net income (loss)	(171)					(168)			(168)		(3)
Shares outstanding, ending balance (in shares) at Mar. 31, 2020			1,000	91,970
Stockholders' equity, ending balance at Mar. 31, 2020	2,066		$ 0	$ 1	1,108	961		0	2,070		(4)
Shares outstanding, beginning balance (in shares) at Dec. 31, 2020			1,000	89,457
Stockholders' equity, beginning balance at Dec. 31, 2020	2,504		$ 0	$ 1	1,126	1,434		(58)	2,503		1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued / (surrendered) under incentive compensation plan (in shares)				1,183
Shares issued / (surrendered) under incentive compensation plan	(19)				(19)				(19)
Share-based compensation	6				6				6
Repurchase of common stock (in shares)				(4,505)
Repurchase of common stock	(148)							(148)	(148)
Net income (loss)	561					561			561		0
Shares outstanding, ending balance (in shares) at Mar. 31, 2021			1,000	86,135
Stockholders' equity, ending balance at Mar. 31, 2021	$ 2,904		$ 0	$ 1	$ 1,113	$ 1,995		$ (206)	$ 2,903		$ 1